Tank monitor



FIG. 1 is a top plan view of the tank monitor embodying the invention;

FIG. 2 is a front view thereof;

FIG. 3 is a rear view;

FIG. 4 is a bottom view;

FIG. 5 is a right side view of FIG. 1; and,

FIG. 6 is a left side elevational view of FIG. 1. 

The ornamental design for a tank monitor, as shown. 